Unreliable expert testimony requires retrial of slip-and-fall case

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A trial court erred when it admitted expert testimony about certain behaviors observed in video footage in a slip-and-fall case, the South Carolina Court of Appeals has ruled, reversing and remanding for a new trial.

Karrie Gurwood and her husband Howard sued GCA Services Group, Inc. after Karrie slipped and fell.

At trial, the court allowed Dr. Leah Hartman – GCA’s expert in human factors psychology – to testify as to her opinion that based on certain behaviors she observed in video footage of the fall, Karrie had some awareness that the floor was slippery.

A jury found GCA and Gurwood were each 50 percent at fault and awarded Karrie half of her current medical expenses but nothing for pain and suffering or future medical costs; jurors also denied Howard’s claim for loss of consortium.

The Gurwoods appealed. Initially, the appellate panel found the trial court erroneously granted GCA’s motion for a directed verdict as to punitive damages and reversed and remanded for a new trial.

Earlier in 2025, the South Carolina Supreme Court affirmed the reversal but remanded to the appellate panel to address the remaining issues on appeal.

In a per curiam opinion in Gurwood v. GCA Services Group, Inc. – authored by Chief Judge H. Bruce Williams and Judges John D. Geathers and Matthew P. Turner – the court reversed and remanded for a new trial based on the erroneous admission of unreliable expert testimony.

The test for reliability for expert testimony does not lend itself to a one-size-fits-all approach, the court explained, and when assessing the reliability of scientific expert testimony, the trial court must consider the four factors outlined by the South Carolina Supreme Court in 1999’s State v. Council: the publications and peer review of the technique; prior application of the method to the type of evidence involved in the case; the quality control procedures used to ensure reliability; and the consistency of the method with recognized scientific laws and procedures.

“Applying the Council factors, we hold the trial court abused its discretion in admitting the testimony because Dr. Hartman failed to provide evidence of any prior application of her method to the type of evidence in this case,” the court wrote.

Dr. Hartman watched a 37-second video of Gurwood’s fall and concluded that “behaviors demonstrated in the video indicate[d] [Karrie] had some form of awareness that she was walking into a slippery environment.”

In particular, Dr. Hartman observed that Karrie’s pre-fall steps resembled her post-fall steps and that she would have expected a difference between the two.

“While this methodology – comparing pre-fall steps with post-fall steps – resembles the technique used in ‘calibration-type’ experiments cited by Dr. Hartman, Dr. Hartman provided no evidence of when a conclusion of this sort has been reached from video footage alone,” the court said. “In other words, there is ‘too great an analytical gap’ between the data – in this case, the very short video – and Dr. Hartman’s conclusion.”

Even if the testimony was nonscientific, Dr. Hartman’s testimony still lacked sufficient indicia of reliability, the court added, as her conclusion rested on the converse of the premise established by her research – not independent verification.

“Without independent verification, Dr. Hartman’s conclusion is unreliable; reliability requires empirical verification that the specific inference relied on by the expert has been successful,” the court wrote.

The trial court erred by admitting her expert testimony and the error was prejudicial “as the evidence likely influenced the jury,” the court added.

Karrie’s knowledge about the dangerous condition was a contested fact relevant to the jury’s assessment of her comparative fault and the jury found her to be 50 percent at fault.

“Given that Dr. Hartman provided the only evidence as to Karrie’s actual knowledge of the slippery floor, there is a reasonable probability that Dr. Hartman’s testimony influenced the jury’s determination of comparative fault, especially considering the instruction that assumption of the risk – which requires actual knowledge of the dangerous condition – could be compared with the defendant’s negligence,” the court said.

The court reversed and remanded to the trial court for a new trial.

Considering the Gurwoods’ other arguments on appeal, the court determined the trial court did not abuse its discretion by denying their new trial motions because the jury’s verdict of damages only for past medical bills was not clearly inconsistent with the evidence presented.

South Carolina law does not require a jury that awards damages for medical costs to also award damages for future medical expenses or pain and suffering, and the verdict was consistent with the evidence presented, the court found.

The court did agree with the Gurwoods that the trial court abused its discretion in excluding testimony from their expert in human factors psychology, but found they were not prejudiced by its exclusion, as the expert was still permitted to describe the safety hierarchy in general and to provide his opinion that it comprised the standard of care applicable to, and breached by, GCA.

The court was not persuaded that a new trial was required because the trial court allowed GCA to impeach Karrie with evidence of her medical insurance, as she opened the door to the evidence by testifying she had not received recommended medical treatment because she could not afford it.

Finally, the court disagreed with the Gurwoods that the trial court abused its discretion in denying their directed verdict motion and charging the jury on assumption of risk because no evidence was presented at trial that Karrie knew of the waxed floor when she fell or that she “appreciated the nature and extent” of the dangers of the waxed floor.

Robert T. Lyles Jr. of Lyles & Associates in Mount Pleasant represented GCA.

“It seems mighty unfair to have to go back and try the whole case again, when there were so many issues decided in the first trial that we won,” he said, adding that he has already filed a petition for rehearing with the Court of Appeals.

The Gurwoods represented themselves pro se.